Landslide Hazards along River Corridors - Rock fall potential

Rock fall is a type of landslide that occurs in bedrock where single or multiple rocks are dislodged and fall from steep cliff faces. In a typical alpine setting, cliffs are located on the upper slopes of a mountain with a talus below, extending to the base of the mountain. The talus is composed of rocks that have fallen from the cliff face and accumulate below the cliff. The talus marks the limit of most rock fall from the cliff, but a few boulders that fall from the cliff travel beyond the toe of the talus. It is these outliers that can pose a hazard to adjacent development (see figure "b" below). Rock fall can be triggered by earthquakes, freeze-thaw cycles, or severe weather. Tumbling boulders falling from a cliff face are fast moving and can level virtually anything in their path.落石（Rock fall）是一类发生于基岩的滑坡类型，指单块或多块岩石从陡峭崖壁崩落脱离的地质现象。在典型的高山环境中，崖壁通常位于山地的上部坡段，其下方分布有延伸至山麓的岩屑堆（talus）。岩屑堆由从崖壁崩落并在崖下堆积的岩石组成，多数从崖壁崩落的落石均以该岩屑堆为堆积范围的边界，但少数崩落的巨砾会越过岩屑堆的趾部。正是这些超出岩屑堆范围的落石孤体，会对周边开发区域构成安全隐患（详见下图b）。落石的诱发因素包括地震、冻融循环以及极端天气。从崖壁崩落的翻滚巨砾移动速度极快，几乎可摧毁行进路径上的所有物体。